Add non-MKL GNU build for Ubuntu 18.04

The new GNU build uses OpenBLAS and Netlib ScaLAPACK (both built from
source) in lieu of Intel MKL.

Added an additional layer to directory tree to distinguish builds with
differing math libraries.

gnu/ubuntu/18.04/Singularity

@@ -0,0 +1,102 @@
+Bootstrap: docker
+From: ubuntu:18.04
+
+%help
+    Test container for the full-potential, all-electron FHI-aims electronic
+    structure package.
+
+%labels
+    MAINTAINER William Huhn ([email protected])
+    VERSION Stupid-User-Version
+
+%runscript
+    /opt/FHI-aims/bin/aims.scalapack.mpi.x
+
+%post
+    # Download the packages we'll need from the Ubuntu repos
+    apt-get update -y
+    apt-get install -y --no-install-recommends \
+        ca-certificates \
+        g++ \
+        gcc \
+        gfortran \
+        git \
+        gnupg \
+        make \
+        openssh-client \
+        wget
+    rm -rf /var/lib/apt/lists/*
+
+    # Download the FHI-aims source code
+    # This step requires user authentication, so do it as soon as possible
+    # As a security measure, we hardwire the known-good host public key here
+    echo 'aims-git.rz-berlin.mpg.de,141.14.177.25 ecdsa-sha2-nistp521 AAAAE2VjZHNhLXNoYTItbmlzdHA1MjEAAAAIbmlzdHA1MjEAAACFBAGjz5fWz7iYO3Y+t/Bo32mVYTO3jFsyHe9L5+6Wr+LGREPN1G0dGDh8nYgsVSDV82M4NHOzRkmrDtw37vkGXIouKABJ2f5XkNgk+xyGdgVf3Bdt7P8AU2bTKY9kXpglSm6OHwOyJqDSHDXSuJNZfKrhWyhZIJsQ0D/l0KxAdy5Cy5eVXg==' >> /etc/ssh/ssh_known_hosts
+    cd /opt
+    rm -rf FHI-aims && mkdir FHI-aims && cd FHI-aims
+    git clone https://aims-git.rz-berlin.mpg.de/aims/FHIaims.git src
+
+    # Download and install Open MPI from source
+    cd /tmp
+    wget https://download.open-mpi.org/release/open-mpi/v3.0/openmpi-3.0.0.tar.gz
+    tar -zxf openmpi-3.0.0.tar.gz && cd openmpi-3.0.0
+    rm -rf build && mkdir build && cd build
+    ../configure CC=gcc CXX=g++ FC=gfortran
+    make -j && make install
+    ldconfig
+    rm -rf /tmp/openmpi-3.0.0.tar.gz /tmp/openmpi-3.0.0
+
+    # Download and install OpenBLAS from source
+    cd /tmp
+    wget http://github.com/xianyi/OpenBLAS/archive/v0.2.20.tar.gz
+    tar -zxf v0.2.20.tar.gz && cd OpenBLAS-0.2.20/
+    make -j && make install
+    rm -rf /tmp/v0.2.20.tar.gz /tmp/OpenBLAS-0.2.20/
+
+    # Download and install NetLib ScaLAPACK from source
+    cd /tmp
+    wget http://www.netlib.org/scalapack/scalapack-2.0.2.tgz
+    tar -zxf scalapack-2.0.2.tgz && cd scalapack-2.0.2
+    cp SLmake.inc.example SLmake.inc
+    make lib
+    mkdir -p /opt/scalapack/2.0.2 && mv libscalapack.a /opt/scalapack/2.0.2/libscalapack.a
+    rm -rf /tmp/scalapack-2.0.2.tgz /tmp/scalapack-2.0.2
+
+    # Create make.sys
+    cd /opt/FHI-aims/src
+    cat <<EOF > make.sys
+###############
+# Basic Flags #
+###############
+FC            = gfortran
+FFLAGS        = -O3 -mavx -ffree-line-length-none
+F90MINFLAGS   = -O0 -ffree-line-length-none
+F90FLAGS      = -O3 -mavx -ffree-line-length-none
+LAPACKBLAS    = /opt/OpenBLAS/lib/libopenblas.a
+
+#########################
+# Parallelization Flags #
+#########################
+USE_MPI       = yes
+MPIFC         = mpif90
+SCALAPACK     = /opt/scalapack/2.0.2/libscalapack.a
+
+################
+# C, C++ Flags #
+################
+USE_C_FILES   = yes
+CC            = gcc
+CXX           = g++
+CCFLAGS       = -O3 -mavx
+CXXFLAGS      = -O3 -mavx
+
+############################
+# Optional C Library Flags #
+############################
+USE_LIBXC     = yes
+USE_SPGLIB    = yes
+EOF
+
+    # Finally, compile FHI-aims
+    make -j scalapack.mpi
+    make clean
+    cd /opt/FHI-aims/bin && mv aims*.scalapack.mpi.x aims.scalapack.mpi.x